1. FIELD OF THE INVENTION
This invention relates to semipermeable membranes and a method of making them, wherein the membrane comprises a copolymer of acrylonitrile and a non-electrolytic, water soluble monomer.
2. DESCRIPTION OF THE PRIOR ART
Polymeric membranes are used as filtration membranes widely in reverse osmosis, ultrafiltration, microfiltration and dialysis. In reverse osmosis, the high molecular weight membranes are used for separating ions or molecules of low molecular weight of not more than several hundreds from solutions. In this case, the membranes are required to be pressure-resistant because a pressure higher than the osmotic pressure of the solution is applied during the process. The processes of ultrafiltration and microfiltration are for the separation of substances of a molecular weight of more than several hundreds. In such cases, the pressure applied is relatively low, i.e., 0.1-15 atms.